1. Field of the Invention
The present invention relates to an active matrix type display apparatus that is suitable for active matrix type display of images, in particular moving images, using for example liquid crystals, and to a driving method for the same.
2. Description of the Related Art
Conventionally, cathode ray tubes (CRTs) and liquid crystal displays (LCDs) are used for television receivers and computer displays. In liquid crystal display devices for image display, a display pattern is formed on the image screen by selective driving of pixel electrodes arranged in a matrix. When a voltage is applied between a selected pixel electrode and the counter electrode in opposition thereto, then the liquid crystal disposed between the electrodes is optically modulated, which can be seen as a display pattern. As a method for driving the pixel electrodes, the active matrix type driving method is known, in which the individual pixel electrodes are arranged in a matrix, and the pixel electrodes are connected to corresponding switching elements and driven. Generally well known as switching elements for selectively driving the pixel electrodes are thin film transistors (TFTs), and switching elements with so-called MIM (metal/insulator/metal) structure.
Liquid crystal display apparatuses are not only used for the display of still images, but also for the display of moving images. However, the display of moving images poses the problem that pronounced after-images can be observed, and that moving features appear to be followed by a tail. A major reason for the problem of after-images is the slow response of the liquid crystals that are ordinarily used, which is several dozen milliseconds. To solve this problem, not only the development of liquid crystals with faster response has been advancing, but as shown in Japanese Unexamined Patent Publication JP-A 4-288589 (1992), efforts are made to compensate the problem of the slow response of the liquid crystal by anticipatorily emphasizing changes of the voltage applied to the pixel electrodes. Also Japanese Unexamined Patent Publication JP-A 9-258169 (1997) discloses the idea of improving the after-images by anticipatorily emphasizing changes of the voltage applied to the liquid crystal for the display of moving images.
However, in recent years, it has been shown that the problem of after-images is not only caused by the slow responsiveness of the liquid crystals, but also by an after-image effect in human eyesight. That is to say, ordinary liquid crystal display apparatuses use hold mode display elements, which hold the voltage information written into the pixel electrodes for one vertical scanning period that lasts until the next writing process in the pixel capacitor between the pixel electrode and the counter electrode in opposition to the pixel electrode, often leading to after-images in human eyesight. When new information is written into the pixels, the information of the old frame, which was written in the previous vertical scanning period, is perceived as an after-image by the human eye. In image display with CRTs, on the other hand, the information is displayed only in the moment when the electron beam hits the screen, and during the remaining period, black display is performed in which nothing is displayed, so that the human eye does not perceive an after-image. Consequently, to realize a high-speed moving image with a liquid crystal display apparatus, it is necessary to display the information only during a portion of each vertical scanning period and to perform black display in which nothing is displayed during the rest of the vertical scanning period, so as to approximate an impulse mode, as is done in the case of CRTs.
FIG. 17 illustrates one idea for improving the after-images of liquid crystals with a pseudo-impulse mode. When the liquid crystal display is performed by transmission-type liquid crystal display, then it is necessary to turn on a backlight. If the backlight is turned off during a portion of each cycle of the vertical scanning signal, a substantially black display is possible. Japanese Unexamined Patent Publication JP-A 64-82019 (1989) discloses the idea of dividing one frame period for driving the liquid crystal to display one image frame into one vertical period in which a scanning signal is applied successively to the plurality of scanning lines Y1, Y2, etc., a liquid crystal response period lasting until display is performed with the driven liquid crystal, and a backlight ON period, so that the backlight is only on for a portion of one frame period. Also Japanese Unexamined Patent Publications JP-A 11-202285 (1999) and JP-A 11-202286 (1999) disclose the idea of partially turning the backlight off.
FIG. 18 shows another idea for displaying a pseudo-impulse mode on a liquid crystal display apparatus. For example Japanese Unexamined Patent Publications JP-A 9-127917 (1997) and JP-A 11-109921 (1999) disclose dividing one frame period into a vertical period and a black writing period, writing the original image display video signal during the vertical period, and writing a black signal to the pixels during the black writing period.
Improving the responsiveness of the liquid crystal by compensation, anticipatorily emphasizing changes of the voltage applied to the pixel capacitors as disclosed in JP-A 4-288589 and JP-A 9-258169, does not improve the after-image effect of human eyesight. And when turning off the backlight to perform display in pseudo-impulse mode as shown in FIG. 17, in the conventional technology disclosed in JP-A 64-82019, the backlight is turned off simultaneously on the entire display screen. Therefore, it is necessary to turn on the backlight after the vertical period, in which signals are written into the pixels in all display regions, and after the liquid crystal response period that lasts until the liquid crystal of the pixels that are scanned and into which the signal is written last has responded sufficiently. This means, the scanning time allotted per scanning line has to be made shorter than in the ordinary case when the backlight is not turned off. For example, when the backlight is turned on for ⅓ of each frame period, and ⅓ of each frame period is taken for the response of the liquid crystal, then the scanning time allotted as one vertical period is only ⅓ of the scanning time in the ordinary case. This corresponds to a display with a driving frequency that is three times as high, which puts a considerable load on the wiring resistances, switching performance of the TFTs, driver performance and the structure of the backlight, leading to lower display quality and higher costs. Moreover, it has also been suggested to shorten the time for the response of the liquid crystal and increase the scanning time serving as the vertical period by sequentially turning a plurality of back lights on and off, as shown in JP-A 11-202285 and JP-A 11-202286. However, also in this conventional technology, the fact that the vertical period for scanning is shorter than before remains unchanged, and there is also the problem of increased costs for the backlight structure.
Also when a black signal is written into the pixels and display is performed in pseudo-impulse mode as shown in FIG. 18, it is necessary to allot a black signal writing time of about one half of each frame period, so that the actual driving frequency is increased, and the same problems occur as in the prior art, in which the backlight is turned off. As a countermeasure, it has been suggested to provide scanning lines and signal lines for the application of the black signal as shown in JP-A 9-127917, but this leads to problems regarding lower yield due to an increased number of lines, an increased number of drivers, and increased costs for the source driver. It has also been suggested to partition the display portion and perform black display and video display in alternation as shown in JP-A 11-109921, but this leads to increased costs because of a more complicated circuit system and a larger number of signal drivers.
It is an object of the invention to present an active matrix type display apparatus, in which a black signal can be written into the pixels and display can be carried out in pseudo-impulse mode, without increasing the number of lines and without increasing the driving frequency, as well as a method for driving the same.
In one aspect of the invention, an active matrix type display apparatus comprises:
a plurality of signal lines;
a plurality of scanning lines intersecting with the signal lines;
switching elements arranged at intersections of the signal lines and the scanning lines, the switching elements being selectively put into a conductive state for a predetermined period of time per vertical period in accordance with a scanning signal on the scanning lines;
pixel capacitors arranged at the intersections and driven by a video signal on the signal lines through the switching elements in the conducting state, an image being displayed depending on a charge state of the pixel capacitors;
auxiliary capacitors associated with respective pixel capacitors, one sides of the auxiliary capacitors being connected to the switching elements;
a plurality of auxiliary capacitor lines, the other sides of the auxiliary capacitors being connected to the auxiliary capacitor lines; and
a driver for driving the auxiliary capacitor lines such that a display luminance is reduced for a predetermined period of time while the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines.
In accordance with the invention, a plurality of signal lines intersects with a plurality of scanning lines, and switching elements are arranged at intersections of the signal lines and the scanning lines to form an active matrix. Pixel capacitors and auxiliary capacitors are formed at these intersections. One side of the auxiliary capacitor is connected to the switching element, and the other side thereof is connected to an auxiliary capacitor line. The switching elements are selectively put into a conductive state for a predetermined period of time per vertical period, in accordance with a scanning signal on the scanning lines. When the switching elements are in the conducting state, the pixel capacitors and the auxiliary capacitors are charged in accordance with the video signal on the signal lines, and an image is displayed in accordance with the charge state of the pixel capacitors. A driver drives the auxiliary capacitor lines (not through the switching elements) such that the display luminance of the pixel capacitors is reduced through the auxiliary capacitors for a predetermined period of time while the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines. Thus, even when the pixel capacitors have been charged in accordance with the video signal on the signal lines and turned into an image display state, the display luminance is reduced by driving the pixel electrodes through the auxiliary capacitors with the driver, and a pseudo-impulse display can be carried out. Conventionally, auxiliary capacitors have been used to improve the image quality by supplementing the insufficient charge capacitance of the pixel capacitors alone, and as these auxiliary capacitors can be used to improve the after-image characteristics, the image quality of dynamic images can be improved without adding new signal lines to the active matrix, increasing the driving frequency or turning the backlight on and off or partitioning the backlight.
With this invention, pixel capacitors and auxiliary capacitors are arranged at the intersections of a plurality of signal lines and a plurality of scanning lines forming an active matrix, and images are displayed in accordance with the charge state of the pixel capacitors. A driver drives through the auxiliary capacitors the auxiliary capacitor lines, and thereby the charge state of the pixel capacitors, such that the display luminance is reduced, so that the after-image characteristics during display of moving images can be improved by pseudo-impulse display, using the auxiliary capacitors provided to reinforce the charge state of the pixel capacitors. The change of the charge state of the pixel electrodes is not accomplished through the switching elements, so that pseudo-impulse display can be carried out without increasing the driving frequency for the pixel capacitors or adding new functions, such as turning the backlight on and off, and an active matrix type display apparatus that is suitable for high speed display of moving images can be realized without involving major increases in cost or deterioration of the image quality.
In another aspect of the invention, an active matrix type display apparatus comprises:
a plurality of signal lines;
a plurality of scanning lines intersecting with the signal lines;
switching elements arranged at intersections of the signal lines and the scanning lines, the switching elements being selectively put into a conductive state for a predetermined period of time per vertical period in accordance with a scanning signal on the scanning lines;
pixel capacitors arranged at the intersections and driven by a video signal on the signal lines through the switching elements in the conducting state, an image being displayed depending on a charge state of the pixel capacitors;
auxiliary capacitors associated with respective pixel capacitors, one sides of the auxiliary capacitors being connected to the switching elements;
a plurality of auxiliary capacitor lines, the other sides of the auxiliary capacitors being connected to the auxiliary capacitor lines; and
a driver for driving the auxiliary capacitor lines such that a signal of the same polarity as the video signal, having a predetermined amplitude is applied at least once per vertical period, while the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines.
In accordance with this aspect of the invention, a plurality of signal lines intersect with a plurality of scanning lines, and switching elements arranged at these intersections to form an active matrix. Pixel capacitors and auxiliary capacitors are formed at the intersections. One ends of the auxiliary capacitors are connected to the switching elements, and the other end is connected to an auxiliary capacitor line. The switching elements are selectively put into a conductive state for a predetermined period of time per vertical period by applying a scanning signal to the scanning lines. When the switching elements are in the conducting state, the pixel capacitors and the auxiliary capacitors are charged in accordance with the video signal on the signal lines, and an image is displayed in accordance with the charge state of the pixel capacitors. A driver drives the auxiliary capacitor lines (not through the switching elements) such that a signal of the same polarity as the video signal, having a predetermined amplitude is applied at least once per vertical period through the auxiliary capacitors to the pixel capacitors while the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines. Thus, even when the pixel capacitors have been charged in accordance with the video signal on the signal lines and turned into an image display state, the display luminance is reduced by driving the pixel capacitors through the auxiliary capacitors with the driver, and a pseudo-impulse display can be carried out. Conventionally, auxiliary capacitors have been used to improve the image quality by supplementing the insufficient charge capacitance of the pixel capacitors alone, and as these auxiliary capacitors can be used to improve the after-image characteristics, the image quality of dynamic images can be improved without adding new signal lines to the active matrix, increasing the pixel driving frequency, or turning the backlight on and off or partitioning the backlight.
With this aspect of the invention, pixel capacitors and auxiliary capacitors are arranged at the intersections of a plurality of signal lines and a plurality of scanning lines forming an active matrix, and images are displayed in accordance with the charge state of the pixel capacitors. A driver drives the auxiliary capacitor lines such that a signal of the same polarity as the video signal is applied at least once per vertical period, so that the after-image characteristics during display of moving images can be improved by pseudo-impulse display, using the auxiliary capacitors provided to reinforce the charge state of the pixel capacitors. The change of the charge state of the pixel capacitors is not accomplished through the switching elements, so that pseudo-impulse display can be carried out without increasing the driving frequency for the pixel capacitors or adding new functions, such as turning the backlight on and off, and an active matrix type display apparatus that is suitable for high speed display of moving images can be realized without involving major increases in cost or deterioration of the image quality.
In the invention it is preferable that with respect to the scanning lines which select the switching elements, the auxiliary capacitors are divided into groups of a plurality of auxiliary capacitors, the group being associated with a plurality of neighboring scanning lines, and that the driver collectively drives all auxiliary capacitor lines connected to a group of auxiliary capacitors.
In accordance with this aspect of the invention, driving for pseudo-impulse display with the pixel capacitors through the auxiliary capacitors can be performed collectively for a plurality of neighboring scanning lines, so that the number of drivers can be decreased, and costs can be reduced.
In the invention it is preferable that the auxiliary capacitor lines driven by the driver are formed in parallel to the scanning lines.
In accordance with this aspect of the invention, one side of the auxiliary capacitor is connected to the switching element to which the scanning signal on the scanning line is applied, and the other side is connected to the auxiliary capacitor line in parallel to the scanning line. In the pseudo-impulse display through the auxiliary capacitors, the driver changes the charge state of the pixel capacitors through the auxiliary capacitor lines, so that luminance can be reduced.
Moreover, with this aspect of the invention, the auxiliary capacitors can be driven through the auxiliary capacitor lines arranged in parallel to the scanning lines such that the display luminance is reduced.
In the invention it is preferable that an active matrix is formed such that the auxiliary capacitor lines connected to the other sides of the auxiliary capacitors driven by the switching elements to which the scanning signal is applied from the scanning lines also serve as the respectively adjacent scanning lines; and
the driver carries out driving for the auxiliary capacitors and driving for scanning the switching elements connected to the adjacent scanning lines.
In accordance with this aspect of the invention, to the scanning lines of the active matrix are connected (i) the switching elements which charge the pixel capacitors and the auxiliary capacitors in accordance with the display signal on the signal lines, and (ii) that side of the auxiliary capacitors charged in accordance with the scanning signal on the adjacent scanning lines that is not connected to the switching element. The driver for driving the scanning lines selectively puts the switching elements into the conducting state and drives the charge state of the pixel capacitors and the auxiliary capacitors charged by the scanning signal charging the pixel capacitors and the auxiliary capacitors and the scanning signal on the adjacent scanning line such that the luminance is reduced through those pixel capacitors, which makes it possible to perform pseudo-impulse display in an active matrix made of scanning lines and signal lines.
With this aspect of the invention, (i) application of the scanning signal for charging the pixel capacitors and the auxiliary capacitors in accordance with the display signal on the signal line, by selectively putting the switching elements into the conducting state through the scanning lines, and (ii) changing the charge state of the pixel capacitors charged by the scanning signal on the adjacent scanning line such that the luminance is reduced through those auxiliary capacitors, can be performed at different times. Since the auxiliary capacitors can be driven with the adjacent scanning lines instead of through the switching elements, the configuration of the active matrix can be simplified, and the manufacturing costs can be reduced.
In the invention it is preferable that the pixel capacitors include a liquid crystal layer arranged between opposing electrodes, and display is performed in normally white display mode, such that display luminance is high when a voltage applied between the electrodes is low, and display luminance is low when the voltage applied between the electrodes is high.
With this aspect of the invention, a liquid crystal layer is disposed between opposing electrodes of the pixel capacitors, and image display is performed in normally white display mode, in which the display luminance is high when the voltage applied between the electrodes is low, and the display luminance is low when the voltage applied between the electrodes is high. Driving through the auxiliary capacitors such that the voltage across the liquid crystal layer is increased, it is possible to provide a black display period, and improve the after-image characteristics during the display of moving images by pseudo-impulse display.
In a further aspect of the invention, a method for driving an active matrix type display apparatus comprising a plurality of signal lines; a plurality of scanning lines intersecting with the signal lines; switching elements arranged at intersections of the signal lines and the scanning lines, the switching elements being selectively put into a conductive state for a predetermined period of time per vertical period in accordance with a scanning signal on the scanning lines; pixel capacitors arranged at the intersections and driven by a video signal on the signal lines through the switching elements in the conducting state, an image being displayed depending on a charge state of the pixel capacitors; auxiliary capacitors associated with respective pixel capacitors, one sides of the auxiliary capacitors being connected to the switching elements; and a plurality of auxiliary capacitor lines, the other sides of the auxiliary capacitors being connected to the auxiliary capacitor lines, the method comprising:
driving the auxiliary capacitor lines, for a predetermined period of the period in which the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines, such that a charge state of the pixel capacitors connected to the switching elements changes to a display luminance reduction side.
In accordance with the invention, a plurality of signal lines intersects with a plurality of scanning lines in an active matrix type display device, and switching elements, pixel capacitors and auxiliary capacitors are formed at the intersections. One side of the auxiliary capacitor is connected to a switching element, and the other side is connected to an auxiliary capacitor line. The switching elements are selectively put into a conductive state for a predetermined period of time per vertical period with a scanning signal on the scanning lines, and the pixel capacitors and the auxiliary capacitors are charged with the video signal on the signal lines. Image display is carried out in accordance with the charge state of the pixel capacitors, and the auxiliary capacitors reinforce the charge state of the pixel capacitors. The auxiliary capacitor lines are driven (not through the switching elements) such that the charge state of the pixel capacitors is changed towards a reduction of the display luminance through the auxiliary capacitors for a predetermined period of time while the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines, so that display with the pixel capacitors is performed for only a portion of each vertical period, and pseudo-impulse display can be performed. Conventionally, auxiliary capacitors have been used to achieve that the voltage between the electrodes at both sides of the auxiliary capacitor in an active matrix type display apparatus substantially does not change during one vertical period. Using these auxiliary capacitors, pseudo-impulse driving can be carried out, including in each vertical period a period for partially reducing the display luminance, so that the capability of displaying moving images can be improved by pseudo-impulse driving without necessitating a display period for luminance reduction that shortens the scanning period during each vertical period, without controlling the backlight, and substantially not changing the configuration of a conventional active matrix type display apparatus.
With this aspect of the invention, a plurality of signal lines intersects with a plurality of scanning lines. Pixel electrodes that are arranged in matrix shape at these intersections are selectively charged with display signals on signal lines through switching elements provided at the intersections, the switching elements being selected by scanning signals on scanning lines. When image display is performed, the auxiliary capacitor lines connected to the auxiliary capacitors used to reinforce the holding of the display voltage by the pixel electrodes are used to provide a period in which the display luminance is reduced and to perform pseudo-impulse display, so that the after-image characteristics can be improved. The high speed display of moving images can be improved by pseudo-impulse display, without adding major changes to the configuration of the active matrix type display apparatus, which uses auxiliary capacitors to reinforce the pixel capacitors, and without an increase of the driving frequency for driving the switching elements, as would be necessary when shortening the overall scanning time. Also, there is no need to turn the backlight on and off for impulse display, or to partition it, so that the image quality for moving images can be improved without major increases in cost.
In a further aspect of the invention, a method for driving an active matrix type display apparatus comprising a plurality of signal lines; a plurality of scanning lines intersecting with the signal lines; switching elements arranged at intersections of the signal lines and the scanning lines, the switching elements being selectively put into a conductive state for a predetermined period of time per vertical period in accordance with a scanning signal on the scanning lines; pixel capacitors arranged at the intersections and driven by a video signal on the signal lines through the switching elements in the conducting state, an image being displayed depending on a charge state of the pixel capacitors; auxiliary capacitors associated with respective pixel capacitors, one sides of the auxiliary capacitors being connected to the switching elements; and a plurality of auxiliary capacitor lines, the other sides of the auxiliary capacitors being connected to the auxiliary capacitor lines, the method comprising:
driving the auxiliary capacitor lines, for a period of time in which the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines, such that a signal of the same polarity as the video signal, having a predetermined amplitude is applied at least once per vertical period.
In accordance with this aspect of the invention, a plurality of signal lines intersects with a plurality of scanning lines in an active matrix type display apparatus, and switching elements, pixel capacitors and auxiliary capacitors are arranged at these intersections. One side of the auxiliary capacitor is connected to the switching element, and the other side is connected to an auxiliary capacitor line. The switching elements are selectively put into a conductive state for a predetermined period of time per vertical period by applying a scanning signal to the scanning lines, and the pixel capacitors and auxiliary capacitors are charged with the video signal on the signal lines. An image is displayed in accordance with the charge state of the pixel capacitors, and the auxiliary capacitors reinforce the charge state of the pixel capacitors. The auxiliary capacitor lines are driven for a period of time in which the switching elements are in the non-conducting state in accordance with the scanning signal on the scanning lines, such that a signal of the same polarity as the video signal and having a predetermined amplitude is applied so that the charge state of the pixel capacitors is changed toward lower display luminance, not through the switching elements but through the auxiliary capacitor lines. Thus, display with the pixel capacitors is performed during a portion of each vertical period, and pseudo-impulse display can be accomplished. Conventionally, auxiliary capacitors have been used to achieve that the voltage between the electrodes at both sides of the auxiliary capacitors in an active matrix type display apparatus substantially does not change during one vertical period. Using these auxiliary capacitors, pseudo-impulse driving can be carried out, including in each vertical period a period for partially reducing the display luminance, so that the capability of displaying moving images can be improved by pseudo-impulse driving without necessitating a display period for luminance reduction that shortens the scanning period during each vertical period, without controlling the backlight, and substantially not changing the configuration of a conventional active matrix type display apparatus.
With this aspect of the invention, a plurality of signal lines intersects with a plurality of scanning lines. Pixel electrodes that are arranged in matrix shape at these intersections are selectively charged with display signals on signal lines through switching elements provided at the intersections, the switching elements being selected by scanning signals on scanning lines. When image display is performed, the auxiliary capacitor lines connected to the auxiliary capacitors used to reinforce the holding of the display voltage by the pixel electrodes are used to apply a signal of the same polarity as the video signal at least once per vertical period, thereby performing pseudo-impulse display and improving the after-image characteristics. Thus, the high speed display of moving images can be improved by pseudo-impulse display, without adding major changes to the configuration of the active matrix type display apparatus, which uses auxiliary capacitors to reinforce the pixel capacitors, and without an increase of the driving frequency for driving the switching elements, as would be necessary when shortening the overall scanning time. Also, there is no need to turn the backlight on and off for impulse display, or to partition it, so that the image quality for moving images can be improved without major increases in cost.
In the invention it is preferable that the pixel capacitors include a liquid crystal layer arranged between opposing electrodes, and display is performed in normally white display mode, such that the display luminance is high when the voltage applied between the electrodes is low, and the display luminance is low when the voltage applied between the electrodes is high.
In accordance with this aspect of the invention, a liquid crystal layer is disposed between opposing electrodes of the pixel capacitors, and image display is performed in normally white display mode, in which the display luminance is high when the voltage applied between the electrodes is low, and the display luminance is low when the voltage applied between the electrodes is high. Driving through the auxiliary capacitors such that the voltage across the liquid crystal layer is increased, it is possible to provide a black display period, and improve the after-image characteristics during the display of moving images by pseudo-impulse display.
Also, with this aspect of the invention, liquid crystal display is carried out in normally white display mode on an active matrix type display apparatus, and pseudo-impulse display is accomplished by providing a partial black display period during the scanning periods, so that the after-image characteristics during display of moving images can be improved.
In the invention it is preferable that the predetermined period of the period in which the switching elements are in the non-conducting state is within a range of 10% to 70% of the period in which the switching elements are selectively put into the conducting state in accordance with the scanning signal on the scanning lines.
In accordance with this aspect of the invention, driving to reduce the display luminance through the auxiliary capacitors is carried out for at least 10% and at most 70% of the period in which the switching elements are selectively put into the conducting state in accordance with the scanning signals on the scanning lines, so that pseudo-impulse display can be performed and the after-image characteristics during the display of moving images can be improved by partially reducing the display luminance, without a major decrease in display luminance or display contrast.
In the invention it is preferable that driving of the auxiliary capacitor lines is carried out such that an absolute value |xcex94Vcs| of a total displacement potential xcex94Vcs between the electrodes of the pixel capacitors which is produced through the auxiliary capacitors satisfies the condition |xcex94Vcs| greater than Vcxc3x97Cp/Ccs, wherein Vc is an intermediate luminance display voltage applied to the pixel capacitors during display, Cp is a total capacitance of a pixel capacitor including a capacitance Ccs of the auxiliary capacitor.
In accordance with this aspect of the invention, due to the change of the charge state of the pixel capacitor through the auxiliary capacitor a change can be applied that is larger than the change of the intermediate luminance display voltage Vc, so that it is possible to improve the after-image characteristics during display of moving images without completely black display in the luminance reduction period.
Also, with this aspect of the invention, driving is performed such that a period is provided in which the luminance is reduced below the intermediate luminance through the auxiliary capacitor lines, so that the after-image characteristics when displaying moving images can be improved by pseudo-impulse display.
In the invention it is preferable that an overshooting voltage is applied at an initial stage when driving the auxiliary capacitor lines.
In accordance with this aspect of the invention, an overshooting voltage is applied at an initial stage of driving through the auxiliary capacitors to perform pseudo-impulse driving, so that reductions of the display luminance can be carried out quickly, and an advantageous pseudo-impulse driving can be carried out without reducing the period in which driving for display luminance reduction is performed.
Also, in this aspect of the present invention, an overshooting voltage is applied initially when driving the auxiliary capacitor lines, so that the display luminance can be reduced quickly, and the effect of after-images can be reduced drastically.
In the invention it is preferable that the voltage is changed stepwise when driving the auxiliary capacitor lines.
In accordance with this aspect of the invention, driving of the display luminance through the auxiliary capacitor lines is performed by changing the voltage stepwise, so that the load on the driver can be reduced, and it becomes easy to collectively drive the auxiliary capacitors, especially when forming groups of scanning lines.
Also, with this aspect of the invention, driving for reducing the display luminance through the auxiliary capacitor lines is performed by changing the voltage stepwise, so that the load on the driver controlling the voltage change through the auxiliary capacitors is reduced.